ACT — Agent Content Tree

Drop-in plugins

One config line in Astro / Next / Nuxt / VitePress / Eleventy / Docusaurus and your site emits ACT alongside its normal output. No bespoke pipeline, no extra hosting.

See the quickstart →

Hosted MCP

Paste 5 lines into Claude Desktop or Cursor and your agent can browse any ACT-emitting site through mcp.act-spec.org. ACT is useful before AI vendors ship native support.

Read more →

Spec + governance

Wire format, conformance levels, JSON schemas — all open. Changes go through the public ASP process. Apache-2.0 reference impl, CC-BY-4.0 spec text, W3C Community Group filing in flight.

Read the spec →

How ACT compares. ACT is a strict superset of /llms.txt and /llms-full.txt — every plugin auto-emits both files for back-compat. ACT adds typed nodes, hierarchy, native i18n, schema validation, and runtime delivery. Different from schema.org (in-page semantics) and sitemap.xml (URL list with no content). Composes with MCP rather than competing. Read the full comparison →

See the token savings yourself

Every example below ships a real, runnable site that emits ACT alongside its normal HTML. Open one in the site browser, click any leaf node, then hit Estimate HTML cost — the meter shows the bytes (and approximate tokens) an agent reads from ACT vs. the same content scraped from HTML.

• Eleventy blog — 33-post chronological feed.
• Astro docs — small typed-doc reference.
• Starlight docs — multi-locale Starlight site.
• VitePress docs — guide + reference + locales.

See every deployed example →

Try ACT with your AI agent

Paste this into your claude_desktop_config.json (or the Cursor / Continue equivalent) and your agent can walk this site — or any ACT-emitting site — immediately.

{
  "mcpServers": {
    "act": {
      "command": "npx",
      "args": ["-y", "@act-spec/mcp-server", "https://act-spec.org"]
    }
  }
}

Copy snippet

Want a hosted MCP server instead? Point your client at https://mcp.act-spec.org over SSE. See the tooling spec for transport details.

Get started

• Have an existing project? Drop a plugin into your build config — see the Quickstart for one-line snippets for Astro, Next.js, VitePress, Nuxt, Eleventy, and Docusaurus.
• Starting fresh? Run npm create act-app@latest and pick from the examples gallery.
• Curious about the wire format? Read the v0.2 specification — manifest, index, node envelopes, conformance levels, and security model.

Tools

• Validator — Paste a URL, JSON, or file to check any ACT artifact against the v0.1 schemas. Runs entirely in the browser.
• Site Browser — Walk and inspect a live ACT-emitting site’s node tree, payload sizes, and conformance gaps interactively.

Status

v0.2.0 is the first public release. The spec is in Draft pending the v0.2.0 stable cut. Reference implementation packages are at @act-spec/* (workspace:* in this monorepo, ^0.2.0 once published). Conformance fixtures and a hosted validator at validator.act-spec.org are part of the same release.